This. And there is one technique that would help in this.

Too often I see code like "xyz := pkg1.SomeFunc(a, b, c)" that makes xyz's type non-evident, especially when interfaces are involved.

Please write Go code like

  var xyz pkg2.SomeType

  xyz = pkg1.SomeFunc(a, b, c)

I don't get it. Why not use a code editor that shows the inferred type on hover?

That should not be an issue, unless the code is written in notepad. As for interfaces, a better approach is to return struct and accept interface in your functions wherever it is possible.